Sawing machine

ABSTRACT

A sawing device for sawing a long object to a fixed size, said sawing device comprising a conveyor (1) for conveying the object to be sawn and blades (3, 4) rotated by a first power unit (2) for cutting the object. The sawing device comprises a rotatable frame (6) rotated by a second power unit (5), the blades (3, 4) being supported by said rotatable frame, a third power unit (7) and guide bars (8, 9) in the rotatable frame to allow the blades (3, 4) to be moved back and forth by the third power unit along the guide bars in the longitudinal direction of the object to be sawn.

BACKGROUND OF THE INVENTION

The present invention relates to a sawing device as defined in theclaims.

Traditonally, long timber is sawn to a fixed size by moving the timberagainst a stopper adjusted to a suitable position with respect to thesaw blade used, so that when the timber is in position the saw bladecuts a piece of desired fixed length off the timber. The fixed-lengthpiece is then removed and the timber to sawn is further advancedlongitudinally against the stopper. In this manner, sawing is continuedin stages by moving the timber and then sawing it.

The main problem with present sawing equipment and methods used to cuttimber to a fixed size is that they are slow, which is due to theintermittent nature of the sawing. As the cutting operation itself is arelatively fast action, most of the time is consumed while the saw bladeis waiting for the timber to be moved into the sawing position againstthe stopper. The slowness of sawing is a particularly bad problem inindustries where there is a need for large quantities of relativelyshort fixed-length timber pieces, for example in furniture industry,prefabricated building industry and parquet industry.

SUMMARY OF THE INVENTION

The object of the invention is to eliminate the drawbacks referred toabove. A specific object of the invention is to produce a new type ofsawing device that enables long timber to be accurately cut intofixed-length pieces in a continuous process as fast as possible.

As for the features characteristic of the sawing device of theinvention, reference is made to the claims.

The sawing device of the invention comprises a conveyor for conveyingthe timber to be sawn and blades for cutting the timber at desiredpoints, said blades being rotated by a first power unit and disposed ina transverse position relative to the lengthways direction of the timberto be sawn. According to the invention, the sawing device comprises arotatable frame rotated by a second power unit and supporting theblades, of which there are preferably at least two. Moreover, the sawingdevice comprises a third power unit and, in the rotatable frame, guiderails along which the blades can be moved back and forth by means of thethird power unit in the direction on the axles of the blades. i.e. inthe longitudinal direction of the timber to be sawn.

Thus, as the axes of rotation of the blades and the axis of rotation ofthe rotatable frame are parallel to each other and parallel to thedirection of motion of the timber to be sawn, it is possible, byrotating the blades and the rotatable frame supporting them, to cut thetimber to a fixed size while the timber is in continuous and steadymotion, by only moving the blades back and forth in the direction oftheir axles at the velocity of motion of the timber.

DETAILED DESCRIPTION OF THE INVENTION

The rotatable frame preferably comprises blade axle disposed at the samedistance from the axle of the rotatable frame and parallel to it.

The blades are preferably supported by separate blade holders movablealong guide bars parallel to the axles of the blades.

The back-and-forth movement of the blades in the direction of theiraxles is preferably implemented using a motion chain, which is connectedto the blade holders and can be moved back and forth.

In a preferred embodiment, none of the power units is mounted on therotatable frame, but the first, second and third power units are mountedoutside the rotatable frame and coupled via concentric axles to therotatable frame.

The third power unit, which moves the blades back and forth in thedirection of the axles, is preferably arranged to work in synchronismwith the conveyor that moves the timber to be sawn, in such manner thatthe velocity of motion of the sawing blade in the direction of its axleis always the same as the velocity of the timber moving on the conveyor.

The sawing device of the invention preferably has two sawing bladesmounted in the rotatable frame, but the number of blades can also beconsiderably larger, in wich a lower speed of rotation of the rotatableframe will result in the same sawing efficiency.

The sawing device of the invention has significant advantages ascompared with prior art. The production of a large number of fixed-sizepieces of wood is not an intermittent but a continuous and smoothprocess in which the timber to be processed is moving at a constantspeed throughout the sawing process. Thus, for example, from a normalboard the sawing device can cut three fixed-size pieces of 60 cm persecond, and even more.

In the following, the invention will be described in detail by referringto the attached drawing, which presents an axonometric diagram of asawing device according to the invention.

The sawing device of the invention presented in the drawing comprises asuitable conveyor 1 together with its power units 18 for moving anobject to be sawn 19 in its lengthways direction. The sawing devicecomprises a rotatable frame 6, which is supported by its axle 12, whichin turn is supported on the frame 20 of the sawing device. Supported onthe frame 20, a second power unit 5 is arranged to rotate the rotatableframe 6 about its axle 12.

Mounted between the two end pieces of the rotatable frame 6 and parallelto the axle 12 are a first pair of guide bars 8 and a second pair ofguide bars 9 as well as a first blade axle 10 and a second blade axle11. Supported on the first guide bars 8 and the first blade axle 10 is afirst blade holder 13, which carries a first blade 3. In the same way, asecond blade holder 14 carrying a second blade 4 is supported on thesecond blade axle 11 and the second guide bars 9. The blade axles 10 and11 are coupled via power transmission belts 21 to an axle 16 concentricwith the axle 12 of the rotatable frame 6 and mounted inside it andcoupled to a first power unit 2, which is mounted on the frame 20, torotate the blade 3 and 4.

The blade holders 13 and 14 supported on the guide bars 8 and 9 areattached to a motion chain 15, which moves back and forth responsive toalternating clockwise and couneterclockwise movement of chain wheels 22.The chain wheels are rotated clockwise and counterclockwise by means ofa third power unit 7, which is coupled to the chain wheels via an axle17 concentric with the axle of the rotatable frame and mounted insideit.

The sawing device presented in the drawings works as follows. The firstpower unit 2 rotates the saw blades 3 and 4 while the second power unit5 rotates the rotatable frame 6 at a suitable speed. The third powerunit 7 moves the blade holders 13 and 14 and the sawing blades 3 and 4rotating with these back and forth in the direction of motion of theobject to be sawn or laterally along the guide bars 8 and 9 so that whenone of the blade holders is moving forward, the other one is movingbackward. Thus, when the device is in operation, as the conveyor 1 ismoving the object at the same speed as the third power unit 7 is movingthe blades in the longitudinal direction of the object, when the sawingblade engages the object, it will be moving at the speed of the object,cut it through and leave the object area before stopping and returningto the first end of the rotatable frame.

Thus, in the sawing device the sawing blade touches the moving object tobe sawn while itself moving at the speed of the object in the samedirection and, after cutting the object, moves aside and returns back tothe starting position of a new sawing operation. At the same time, theother saw blade performs corresponding sawing and returning actions onthe opposite side of the common rotation axis of the saw blades.

The synchronization of the motors in the sawing device and of theirmovements can be implemented using electronic or mechanical means knownin themselves. The blades 3 and 4 are preferably rotated continuously bymeans of the first power unit 2, but the rotation of the rotatable frame5 by the second power unit 5 and the back-and-forth motion of the bladeholder produced by the third power unit 7 may be either continuous orintermittent according to need, depending e.g. on the quality of theobject to be sawn, on the blades being used, the length of the pieces tobe cut, and so on.

The invention has been described above as an example by the aid of theattached drawing, but different embodiments of the invention arepossible within the framework of the inventive idea defined by theclaims.

What is claimed is:
 1. A sawing device for sawing a long object to afixed size, said sawing device comprising:a conveyor (1) for conveyingthe object to be sawn at a certain speed in a direction of motion from astarting position of a sawing operation, blades (3,4) rotated by a firstpower unit (2) for cutting the object; a rotatable frame (6) rotated bya second power unit (5), the blades (3,4) being supported by saidrotatable frame, a third power unit (7); and the rotatable frame (6)having guide bars (8,9), the blades (3,4) being supported by bladeholders (13,14) movable along the guide bars (8,9), so that when sawingthe object the third power unit moves one of the blade holders andblades in the direction of motion at the speed of the object when at thesame time the other blade holder and the blade is moved opposite thedirection of motion to the starting position for a new sawing operation.2. A sawing device as defined in claim 1, wherein the rotatable frame(6) comprises blade axles (10,11) disposed at a like distance from andparallel to an axle (12) of the rotatable frame.
 3. A sawing device asdefined in claim 1, wherein the blade holders (13,14) are connected to amotion chain (15) which is moved back and forth.
 4. A sawing device asdefined in claim 1, wherein the first, second and third power units(2,5,7) are coupled via concentric respective axles (16,12,17) to therotatable frame (6).
 5. A sawing device as defined in claim 1, whereinthe third power unit (7) is arranged to move the blades (3,4) at thespeed of motion of the object to be sawn and in the direction of motionof the object (1).
 6. A sawing device as defined in claim 1, wherein theblades (3,4) are discoid circular-saw blades.
 7. A sawing device asdefined in claim 1, wherein the object to be sawn is timber.